I think this is likely the explanation. There isn't a food that "flips it on" it's always been on in some people and in others they are either highly resistant to this process or it is age-dependent. Fortunately the solution is to not eat the foods that this process depends on. I think this an important point because you can either wait for therapies that target these processes or simply stop eating crap and accept that some people are more able to eat crap than you are.

Since I've cut processed food and bread entirely out of my diet I've lost a lot of weight pretty effortlessly. I don't think this experience is unique. I also know people that can eat lots of these foods without weight gain.